The face of a god

When a spiritual being appears in a story, I sometimes ask why this face specifically with specific facial shapes.

• The face of this old man, who looks to have a wealth of knowledge and experience worthy of being called an "elder".
• A wise child, though still young. In other words, this face tests one's will to raise a hand against a child.
• The feminine form of the faces. There is a hint of sadness in it, which may be due to its effect on the people being judged.
• The face of a mature man. His hair brushed back, chin up, and condescending gaze are intimidating, the shape of his eyebrows and eyes suggest a stern and domineering personality. Without confidence and courage in yourself, just facing them may cause you to shy away.

Babel's four faces, representing each stage of life: child, two middle-aged and old, remind us of the Buddhist concept of the four sufferings, birth, aging, sickness, and death, as well as the Sphinx's riddle of "a creature that goes on four legs in the morning, two legs in the afternoon, and three legs in the evening". In fact, Babel's role is similar to that of the Sphinx, being the one who determines the path followed by the player and their growth in response to the "stages of human life," the solution to the riddle.
Babel itself is a mere device to determine whether the hero is worthy of being the "master" of the Bel gods, or in other words, the reigning king. Therefore, all four faces are, for the most part, expressionless. The face chosen most likely adapts to what is most effective on the people being judged.
In the book of Ezekiel, the Angels of Wisdom are described as having four different faces and four wings. The faces of the cherubim are different from Babel's: human, lion, ox, and eagle, but they are considered to be the vehicles of the gods, a fusion of man and beast, much like the Sphinx.
-- Kazuma Kaneko Works IX, Devil Survivor, Babel

For humans, the appearance has biological factors. So when a god, an ancient spirit, or an artificial creation has a human face, where it came from? If a spiritual being has a specific human face, there has to be a specific reason. This is an extremely overlooked detailed, but an author paying attention to it can greatly enhance their worldbuilding.

Self-representation

The face was carefully designed by the being themselves out of many references, choosing the appearance that they think represents them the best. It's meant to inspire trust, desire, fear, nostalgia, or authority, and is used as a tool. Or maybe they've designed their face for an aesthetic reason of identity or expression, the way someone would chose a clothing. Sometimes such faces may appear distorted due to being a mimicry without comprehension of human facial grammar. Alternatively, the being may adopt the appearance of a specific human for some personal reason based on personal factors, with the motive for the borrowing telling a lot about the personality. If it's not the being's true form, it'd at least be the default one or one of many.

Projection from the observers

The face isn't generated intentionally, but is rather a collective amalgamation of what humans expect the being to look like. Such often represent local culture and mythology, using a human anatomy in place of an avatar as the closest thing the morals understand, followed by local animals. In some cases, the humans may gift the being an appearance through an idol or a painting. Depending on the psyche, the being may appear motherly or monstrous depending on the relationship cultivated.

Residual humanity

The face is the being's own because they are a ghost or an ascended ancestor, making the appearance a biological artifact. The anatomy reflects how they've lived, and some beings may stick with it even if they have the opportunity to alter it completely. The being may also have been stealing faces from their pray or followers and presenting them as their own.

Doylist reality

This is generally the case most of the time, the author simply didn't give it much thought. The narrative needs to point at a character, so someone should be there, making the appearance the author's personal preference or the consequence of the actor portraying them. In a visual medium, it sacrifices viewer's imagination by giving an abstract character an arbitrary form. Generally, it's not expected to be something that is questioned, however in some cases there may be a narrative reason why a specific face was used.

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